Four studies of normal and ulcer-operated patients are proposed to delineate post-operative alterations in normal mechanisms balancing rates of gastric emptying with subsequent alimentary events. In patients with subtotal gastric resection or with vagotomy and "drainage" procedures, the goal is to determine whether previously observed low postcibal luminal concentrations of pancreatic and biliary secretions result from 1) deficient postcibal pancreatic and biliary secretion, 2) normal secretory rates but luminal dilution of pancreatic enzymes and bile salts by rapidly emptying gastric contents, or 3) some combination of 1 and 2. To achieve this goal a newly developed intestinal dilution indicator technique will be utilized as an index of secretory output and gastric emptying. In normal patients and in ulcer-operated patients relationships between rates of gastric emptying and blood concentrations of glucose will be explored to determine whether rates of glucose absorption may be controlled by rates of carbohydrate emptying from the stomach and to determine whether such a process is defective in ulcer- operated patients predisposing them to abnormalities in glucose homeostasis. Either a double dilution gastric indicator technique or the intestinal indicator technique will be used in these experiments. Finally, an intestinal indicator technique will be utilized to determine the source of abnormal fluid fluxes in patients with postvagotomy diarrhea. All studies are deemed feasible based on validated techniques and preliminary results.